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FIGURE 13 Benefits of histograms of vector-valued data. These figures show histograms of an object consisting of three materials. (a) This histogram of scalar data shows that material mean values are collinear. Distinguishing among more than two materials is often ambiguous. (b) and (c) are two representations of histograms of vector-valued data and show that mean values often move away from collinearity in higher dimensions, and so materials are easier to distinguish. High/bright locations indicate more common (v0, vj) data values. While less likely, (d) shows that the collinearity problem can exist with vector-valued data.